Fuel cell with anode containing a catalyst composition of iridium and ruthenium

ABSTRACT

1. In a fuel cell comprising an anode, a cathode and an electrolyte positioned between and communicating with said anode and cathode, the improvement wherein said anode comprises a catalyst composition consisting essentially of co-reduced iridium and ruthenium where the atom ratio of each component to the total catalyst is in the range of from 25 to 75 percent.

United States Patent Batzold 1451 Apr. 25, 1972 s41 FUEL CELL WITH ANODE 3,291,753 12/1966 Thompson .252/447 CONTAINING A CATALYST 3,276,976 10 1966 .luliard ..204 43 COMPOSITION OF IRIDIUM AND OTHER PUBLICATIONS RUTHENIUM [72] Inventor: John S. Batzold, Westfield, NJ.

[73] Assignee: Esso Research and Engineering Company [22] Filed: July 16, 1969 [21] Appl. N0.: 847,500

Related U.S. Application Data [63] Continuation of Ser. No. 381,899, July 10, 1964.

[52] U.S.Cl ..l36/86 D, 136/120 FC [51] Int. Cl ...H0lm 27/04, l-[Olm 13/06 [58] Field of Search ..136/86, 120

[56] References Cited UNITED STATES PATENTS 3,223,556 12/1965 Cohn ..136/86 3,287,171 11/1966 Holt ..136/120 Mellor, Comprehensive Treatise on Inorganic & Theoretical Chemistry Vol. 15 Longmans, Green and Co., N.Y. 1936 QD3 1 M4 pp. 747

Primary Examiner-Winston A. Douglas Assistant Examiner-M. J. Andrews Attorney-Whelan, Chasan, Litton, Marx & Wriglet and Henry Berk EXEMPLARY CLAIM 1. In a fuel cell comprising an anode, a cathode and an electrolyte positioned between and communicating with said anode and cathode, the improvement wherein said anode comprises a catalyst composition consisting essentially of coreduced iridium and ruthenium where the atom ratio of each component to the total catalyst is in the range of from 25 to 75 percent.

4 Claims, N0 Drawings FUEL CELL WITH ANODE CONTAINING A CATALYST COMPOSITION OF IRIDIUM AND RUTI-IENIUM This application is a continuation of Ser. No. 381,899, filed July 10, 1964.

Heretofore in the art, noble metal catalysts containing platinum were required in systems utilizing an acid electrolyte. Various nonplatinum materials and mixtures thereof were tried as catalysts but none were particularly efficient.

It has now been found that a particular combination of noble metals containing no platinum will function efficiently as the catalyst in a system utilizing either an acidic or basic electrolyte.

The catalyst of this invention consists of iridium which is useful as a catalyst in certain systems but is not too efficient and ruthenium which is not effective as a catalyst since it polarizes to a value greater than one at very low current densities. Therefore, for all practical purposes, ruthenium is inactive as a catalyst.

The catalyst of this invention can be used as a catalyst in chemical reactions to initiate or accelerate reactions in anodic oxidations and cathodic reductions, in hydrogenation reactions, hydrocracking reactions and in polymerization reactrons.

The catalyst of this invention is made by coreducing a mixture of ruthenium and iridium salts. The mixture of salts can be in solution or supported upon a body. The reduction can be by chemical means such as reduction with NaBH,, KBH;,, formaldehyde, formic acid, diborane or the radical anion procedure as set forth in U.S. Pat. No. 2,177,412. The materials may also be reduced with gases such as hydrogen and CO at low temperatures or at elevated temperatures of greater than 800 F.

Examples of salts which can be used in the production of the instant catalyst include RuCl RuCl,,-4H O, Ru(OH) RU02'XH2 U lrBr '4H O, lrBr,,, IrCl lrCl.,, lrl lr O lr O -xH O, lr( OH lr S [I5 and Ir(HS) -2H O. The foregoing salts are put into solution and then reduced. The finely divided precipitate is then washed with water and soaked in an alkali metal hydroxide such as NaOl-l, KOl-l and LiOH or other basic solutions having a pH greater than 9 for from 0.02 to 30 hours. The materials are then washed and are ready for use. The finely divided precipitate will be in a lower oxidation state than when it was in the salt. In some cases, the oxidation state will be zero.

The catalyst of the present invention comprises a combination of iridium and ruthenium. The ratio of ruthenium to the total catalyst is in the range of from 25 to 75 atom percent and the ratio of iridium to the total catalyst is in the range of from 75 to 25 atom percent. The preferred ratio is a 50/50 mixture.

The following examples are submitted for the purpose of illustration only and are not to be construed as limitations upon the scope of the invention as set forth in the appended claims.

EXAMPLE 1 formance data are set forth in Table 1 below.

TABLE I Volts polarized from theoretical methanol at indicated maJern. Catalyst atom, percent 10 60 T00 100-iridium 0. 47 0. 50 0. 52

TABLE I Continued Volts polarized from theoretical methanol atinrllcatml Him/17ml It can be seen from Table I that by coreducing ruthenium, an inactive catalyst, with iridium, a very poor catalyst, one gets a very effective catalyst.

EXAMPLE 2 A mixture of iridium and ruthenium salts is reduced by treatment in accordance with the procedure set forth in U.S. Pat. No. 2,177,412 and the finely divided precipitate is then soaked in NaOl-l for about 15 hours. The material so produced is an effective catalyst.

EXAMPLE 3 Two catalysts were made. Catalyst A was the coreduction in accordance with this invention and the second catalyst consisted of a physical mixture of ruthenium and iridium. This catalyst is denoted B. Catalyst A was made by immersing silica gel in a 50/50 solution of ruthenium and iridium chloride salts. The silica gel was then dried and then immersed in an aqueous potassium borohydride reducing solution in order to reduce the metal ions of the salts. The silica gel was then dried and immersed in a 6N KOH solution in order to dissolve the silica gel. Catalyst B was made by reducing iridium from a solution of a salt with sodium borohydride and separately reducing ruthenium from a solution of its salts with sodium borohydride and then physically mixing the two reduced metals. Catalysts A and B were then tested as theanode catalyst in a fuel cell utilizing methanol as the fuel, air as the oxidant and 30 wt. percent sulfuric acid as the electrolyte. The results of these tests are set forth in Table 11 below.

TABLE II Volts polarized from theoretical 1. in a fuel cell comprising an anode, a cathode and an electrolyte positioned between and communicating with said anode and cathode, the improvement wherein said anode comprises a catalyst composition consisting essentially of coreduced iridium and ruthenium where the atom ratio of each component to the total catalyst is in the range of from 25 to 75 percent.

2. In a fuel cell as defined in claim I, the improvement wherein said catalyst composition consists essentially of a coreduced combination of 50 atom percent ruthenium.

3. In a fuel cell comprising an anode, a cathode, an electrolyte positioned between and communicating with said anode and cathode, fueling means for supplying methanol to said anode, and means for supplying an oxidant to said cathode, the improvement wherein said anode comprises a catalyst composition consisting essentially of coreduced iridium and ruthenium where the atom ratio of each component to the total catalyst is in the range of from 25 to 75 percent.

4. In a fuel cell as defined in claim 3, the improvement wherein said catalyst composition consists essentially of a coreduced combination of 50 atom percent ruthenium. 

1. IN A FUEL CELL COMPRISING AN ANODE, A CATHODE AND AN ELECTROLYTE POSITIONED BETWEEN AND COMMUNICATING WITH SAID ANODE AND CATHODE, THE IMPROVEMENT WHEREIN SAID ANODE COMPRISES A CATALYST COMPOSITION CONSISTING ESSENTIALLY OF COREDUCED IRIDIUM AND RUTHENIUM WHERE THE ATOM RATIO OF EACH COMPONENT TO THE TOTAL CATALYST IS IN THE RANGE OF FROM 25 TO 75 PERCENT.
 2. In a fuel cell as defined in claim 1, the improvement wherein said catalyst composition consists essentially of a coreduced combination of 50 atom percent ruthenium.
 3. In a fuel cell comprising an anode, a cathode, an electrolyte positioned between and communicating with said anode and cathode, fueling means for supplying methanol to said anode, and means for supplying an oxidant to said cathode, the improvement wherein said anode comprises a catalyst composition consisting essentially of coreduced iridium and ruthenium where the atom ratio of each component to the total catalyst is in the range of from 25 to 75 percent.
 4. In a fuel cell as defined in claim 3, the improvement wherein said catalyst composition consists essentially of a coreduced combination of 50 atom percent ruthenium. 